1. Field of the Invention
The present invention relates generally to photovoltaic roofing systems. The present invention relates more particularly to photovoltaic roof arrays and wiring systems for use therewith.
2. Technical Background
The search for alternative sources of energy has been motivated by at least two factors. First, fossil fuels have become more and more expensive due to increasing scarcity and unrest in areas rich in petroleum deposits. Second, there exists overwhelming concern about the effects of the combustion of fossil fuels on the environment, due to factors such as air pollution (from NOx, hydrocarbons and ozone) and global warming (from CO2). In recent years, research and development attention has focused on harvesting energy from natural environmental sources such as wind, flowing water and the sun. Of the three, the sun appears to be the most widely useful energy source across the continental United States; most locales get enough sunshine to make solar energy feasible.
There are now available components that convert light energy into electrical energy. Such “photovoltaic cells” are often made from semiconductor-type materials such as doped silicon in either single crystalline, polycrystalline, or amorphous form. The use of photovoltaic cells on roofs is becoming increasingly common, especially as device performance has improved. They can be used, for example, to provide at least a fraction of the electrical energy needed for a building's overall function, or can be used to power one or more particular devices, such as exterior lighting systems.
Photovoltaic roofing elements can be used to provide weather protection, like standard roofing elements, as well as photovoltaic power generation. Many such photovoltaic roofing elements take the form of a standard roofing element, such as a shingle or a tile, with one or more photovoltaic cells disposed thereon or integrated therewith. Photovoltaic roofing elements are generally difficult to install, as they must not only be physically connected to the roof in a manner that provides weather protection but also be electrically interconnected into a wiring system to be connected to the elements of a larger photovoltaic generation system (e.g., inverters, batteries and meters). Such installation often requires an electrical specialist to perform the electrical interconnections, which can be difficult to time appropriately with the physical installation of the photovoltaic roofing elements. Moreover, relatively large voltage differences (e.g., 100-600 V) are created in many photovoltaic roofing systems. As such, it is desirable to protect the electrical interconnections from the weather so as to avoid arcing and short circuits.
Accordingly, there remains a need for photovoltaic roofing systems having ease of both physical and electrical installability and in which electrical interconnections are protected from the weather.